The lighting system of the present invention has many applications, and, in fact, may be used wherever high illumination levels are to be directed upon a designated site. The lighting system is particularly suited for light levels of 1000 lumens or more on a specifically defined task spot or area. The lighting system of the present invention lends itself well, for example, to medical lighting in general, such as doctors' examination lighting, ambulatory surgical lighting, emergency room lighting, dental lighting and the like. The system of the present invention is not limited in its application to medically related fields. For example, the lighting system may also be directed to scientific applications, architectural applications, and the like.
While not intended to be so limited, for purposes of an exemplary showing, the lighting system of the present invention will be described in its application to surgical lighting of the type found in an operating room.
In general, prior art surgical lighting systems comprise a lighthead containing a light source, a suspension system for the lighthead, and a wall mounted control panel for the system. Typically, one or more bulb-type light sources are contained within the lighthead assembly together with light bulb filtration means, control reflectors, refractors and the like. For the most part, there has not been much in the way of dramatic changes in surgical lighting systems from those systems developed in the 1930's and 1940's. Through the years, light bulbs have become smaller. Tungsten-halogen incandescent lamps have been available since the 1960's and 1970's. More technologically advanced filtration systems have also become available.
Despite these advances, the need for extremely high illumination levels at the operating site has resulted in a number of constraints which limit the overall performance of prior art surgical lighting systems. For example, very high wattage lamp sources are being used in the lightheads of surgical lighting systems. This creates problems with respect to the amounts of electrical power that must be conducted into the operating room through the lighting suspension system and into the lighthead.
There are a number of light sources which are extremely efficient, such as a metal halide type arc lamp. Currently, however, arc lamps cannot be used in existing surgical light designs because the power required to start and operate them in the lighthead would be prohibitive from the standpoints of a power delivery, cost, weight and packaging. Typically, metal halide arc lamps require a very high voltage pulse to restart the lamps if there is a momentary power interruption. This high voltage restart requirement is one constraint which currently prohibits these lamps from being placed in current surgical lighting systems.
Another constraint faced by prior art systems is that of heat. The total light energy delivered to the surgical site is limited by the heat energy in the lighthead. Thermal energy exits the lighthead and is directed to the surgical site. Furthermore, the thermal energy creates problems of drying the tissue at the surgical site, and also causes surgeon discomfort. Currently, the most widely used lamp technology (tungsten-halogen lamps) is limited to a maximum of about 250 watts of power because of the total heat generated by the lighthead system. The thermal energy inside the lighthead causes additional problems with components inside the lighthead, and with contact temperatures on the outside surfaces of the lighthead.
The degree of sophistication of filter applications to minimize unwanted wave lengths and thermal heat in the light beam coming out of the lighthead, and to provide various color temperatures of the light beam output for various types of surgeries, is limited by the fact that present day filter systems must be located within the lighthead. This adds weight, bulk, and thermal energy to the lighthead.
Finally, a major constraint limiting overall performance of prior art surgical lighting systems is the size and weight of the overall system, including, in particular, the lighthead. Typical prior art lightheads are very bulky and heavy, many falling within the range of from about 20 to about 30 pounds or more. This fact complicates the suspension and mounting design of the system. In addition, electrical power must be carried through the suspension system to and into the lighthead. The lighthead should move easily, requiring very little effort on the part of the operator. The lighthead should stay in position where it is placed without drift and should be easily adjusted by the surgeon or a circulating nurse. The size, bulk and weight of prior art lightheads make these goals very difficult and very expensive to achieve, requiring large counterbalancing systems and the like.
The size and bulk of current lighting systems also interfere with the crowded ceiling and the overall nature of the operating room. The lighting, air flow system, monitors and other equipment required to be contained within the operating room environment, places a premium on the size and weight and complexity of operating room lighting designs.
The present invention is based upon the discovery that the various constraints and problems outlined above can be overcome by locating the light source remote from the lighthead. Light energy from the light source is transported to the lighthead by light piping material. A light source module will be provided which can be located in a part of the suspension system of the lighting system, in the ceiling of the operating room, or in any location exterior of the operating room. The term "remote" as used herein and the claims is to be interpreted broadly enough to cover all three situations.
Depending upon its location, electrical power limitations are greatly reduced or eliminated. The nature of the light source is not limiting, and use can be made of the highly efficient metal halide arc lamps. There will be virtually no heat associated with the lighthead. As a consequence of all this, regulatory code difficulties with respect to electrical power and heat will be far more easily met.
The remote location of the light source module enables highly sophisticated filter techniques to be employed, since the filter elements need no longer be located in the lighthead. There is no problem in providing a back-up lamp in the light source module, the back-up lamp having the ability to provide identical optical performance to that of the main lamp. This was not always achievable when the back-up lamp was required to be located in the lighthead where optimum location therefor was not always available.
A control panel for the lighting system can be wall mounted, or otherwise appropriately mounted, in the operating room for easy access. The control panel will provide means for turning the lighting system on and off, adjusting the light intensity and, if desired, adjusting color temperature of the light.
The lighthead, in accordance with the practice of the present invention, can be very much thinner and of greatly reduced weight. The lightheads of the present invention will weigh about 10 pounds or less, and preferably about 5 pounds or less. The lightheads taught herein may have a thickness of about two inches or less, as opposed to prior art lightheads having a thickness of 7 to 10 inches, or more. With the light source remote from the lighthead, it is possible to provide a plurality of lightheads provided with quick connect means with respect to the suspension system. The lightheads may differ in size and may be characterized by different light collecting and directing characteristics, as will be described more fully hereinafter. Since the lightheads can be far less bulky and markedly reduced in weight, the suspension systems therefor can be far lighter, less complex and less bulky, large counterweight devices not being needed. Finally, as will be apparent hereinafter, the overall lighting system of the present invention can be far easier and less expensive to manufacture.